The present apparatus and method relate to airbag deployment control systems.
Many vehicles these days are equipped with new active safety system technologies, such as autonomous emergency braking (AEB) by the vehicle based on radar and/or camera and/or Lidar based sensing systems. This type of active safing system is to help mitigate occupant injuries by either avoiding crashes or by reducing the crash speed. However, this AEB can result in an unintended situation where it causes the occupant to be out of position and close to the airbag when the vehicle brakes itself. This can result in increased injuries for the occupant from the out of position (OOP) if the airbag deployment control logic does not take this into consideration.
In order to avoid this unintended situation from happening, overall deployment control logic for the occupant restraint systems is getting more complicated. Finding the most optimized airbag deployment time is critical to provide the maximum protection to the occupant in the accident. Unfortunately, most vehicles even equipped with current active safety systems, still have airbag systems that deploy airbags based on traditional crash sensing parameters. Generally, a traditional crash sensing system must meet safing, and deployment arming requirements before commanding airbag deployment. This is to ensure that airbag is not deployed by accident in a situation where airbag deployment is not warranted and airbag deployment is reserved only as a last resort to provide protection for the occupants.
Typically, earlier airbag deployment is better. However, the capability for fast deployment is often limited by the timing required to satisfy safing and arming criteria. Typically, in order to meet the safing requirement, the sensing system requires a minimum of two consecutive crash signals above a pre-determined deceleration threshold from a safing sensor. As the safing sensor runs at a certain frequency, this will affect overall airbag firing time. For example, for a safing sensor running at 100 Hz, the earliest firing of the airbag system will be a minimum of 10 msec.
FIG. 1 shows prior art safing logic for a traditional passive airbag system.
When a crash occurs as the vehicle is moving, the vehicle deceleration is typically detected as a series of signals at the safing sensor frequency. If the deceleration at any sample period is less than a predetermined deceleration threshold, nothing happens. However, when both the first signal An and a second signal An+1 are greater than the predetermined deceleration threshold the airbag system is armed. If the arming and deployment criteria are then met, the airbag and pretensioner deploys.
However, the requirement of a minimum of two consecutive deceleration measurements which exceed the deceleration threshold set for a crash must be met. The time interval between two consecutive deceleration measurement points depends on the frequency of the safing sensor. For example, if the safing sensor runs at 100 Hz., the time interval between two consecutive samples is 10 msec. As a minimum of two consecutive points must meet the deceleration threshold value in order to meet the safing condition, the safing condition requirement has a minimum 10 msec delay
This delay becomes critical in an airbag deployment since the airbag should be at full deployment and inflation when impacted by the vehicle passenger for maximum passenger safety. If the airbag is not at full deployment when the passenger impacts the airbag, as could result from a delay in initiating the deployment of the airbag, the maximum safety afforded by the airbag to the passenger may not be utilized.